page_title: Anahim hotspot
section_title: Extensional tectonics
hierarchical_section_title: Anahim hotspot / Tectonic history / Extensional tectonics
caption_attribution_description: English: This is a map showing the location and delineation of Queen Charlotte Sound, Hecate Strait, and Dixon Entrance.
context_page_description: The Anahim hotspot is a volcanic hotspot located in the West-Central Interior of British Columbia, Canada. One of the few hotspots in North America, the Anahim plume is responsible for the creation of the Anahim Volcanic Belt. This is a 300 km long chain of volcanoes and other magmatic features that have undergone erosion. The chain extends from the community of Bella Bella in the west to near the small city of Quesnel in the east. While most volcanoes are created by geological activity at tectonic plate boundaries, the Anahim hotspot is located hundreds of kilometres away from the nearest plate boundary.
  This hotspot's existence was first proposed in the 1970s by three scientists who used John Tuzo Wilson's classic hotspot theory. This theory proposes that a single, fixed mantle plume builds volcanoes that then, cut off from their source by the movement of the North American Plate, become increasingly inactive and eventually erode over millions of years. A more recent theory, published in 2001 by the Geological Society of America, suggests that the Anahim hotspot might be supplied by a mantle plume from the upper mantle rather than a deep-seated plume proposed by Wilson.
context_section_description: Rifting and crustal extension in Queen Charlotte Sound up to about 17 million years ago has been linked to the Early Miocene passage of the Anahim hotspot. Yorath and Chase (1981) proposed that subcrustal melting above the Anahim plume resulted in weakening of the regional crust, setting the stage for rift development. Later, widespread volcanism produced subearial basalt and rhyolite flows in the region of the rift and along transcurrent faults that extend towards the northwest. Haida Gwaii was displaced approximately 70 km (43 mi) to the north along a series of faults extending through Sandspit and Louscoone Islet. This period of rifting and crustal extension contributed to the formation of the Queen Charlotte Basin.
  While the rift was in development, a conservative plate boundary would have extended northwards from the landward end of the rift. Such a plate boundary might have been similar to the Gulf of California – San Andreas fault system in the U.S. state of California. This type of configuration need have existed for only a few million years to have generated the 70 km (43 mi) of opening in the rift. Alternatively, the Haida Gwaii block may have been only partially coupled to the offshore plate during a longer period of oblique convergence. Bathyal sediments, perhaps as young as 15 million years, were deposited within the rift zone during and after the rifting took place as the Anahim hotspot passed by.
caption: Queen Charlotte Sound as delineated by BC Geographical Names, along with Hecate Strait and Dixon Entrance.
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